3Preliminaries IDemand curve shows how much consumers would buy of a particular good at any particular price.It is based on optimisation exercise:Would one more be worth price?Market demand is aggregated over all consumers’ demand curves.Horizontal sum.
4Preliminaries ISupply curve shows how much firms would offer to the market at a given price.Based on optimisation:Would selling one more unit at price increase profit?Market supply is aggregated over all firms.Horizontal sum.A firm’s supply curve is its marginal cost curve.
5Welfare analysis: consumer surplus Since demand curve based on marginal utility, it can be used to show how consumers’ well-being (welfare) is affected by changes in the price.Gap between marginal utility of a unit and price paid shows ‘surplus’ from being able to buy c* at p*.= MU
6Welfare analysis: consumer surplus If the price falls:Consumers obviously better off.Consumer surplus change quantifies this intuition.Consumer surplus rise, 2 parts:Pay less for units consumed at old price; measure of this = area A.A = Price drop times old consumption.Gain surplus on the new units consumed (those from c* to c’); measure of this = area B.B = sum of all new gaps between marginal utility and price
7Welfare analysis: producer surplus Since supply curve based on marginal cost, it can be used to show how producers’ well-being (welfare) is affected by changes in the price.Gap between marginal cost of a unit and price received shows ‘surplus’ from being able to sell q* at p*.S=MC
8Welfare analysis: producer surplus If the price rises:producers obviously better off.Producer surplus change quantifies this intuition.producer surplus rise, 2 parts:Get more for units sold at old price; measure of this = area A.A = Price rise times old production.Gain surplus on the new units sold (those from q* to q’).measure of this = area B.B= sum of all new gaps between marginal cost and price.
9Preliminaries IIIntroduction to Open Economy Supply & Demand Analysis.Start with Import Demand Curve.This tells us how much a nation would import for any given domestic price.Presumes imports and domestic production are perfect substitutes.Imports equal gap between domestic consumption and domestic production.
14Trade volume effect & border price effect Decomposing Home loss from price rise, P’ to P”.Area C: Home pays more for units imported at the old price.Area C is the size of this loss.Home loses from importing less at P”.area E measures loss.marginal value of first lost unit is the height of the MD curve at M’, but Home paid P’ for it before, so net loss is gap, P’ to MD.adding up all the gaps gives area E.HomeimportsMDMM’P”CEDomestic priceP’
15Trade volume effect & border price effect HomeimportsMDMM’P”CEDomestic priceBorder price effectTrade volumeeffectP’Systematic net welfare analysis using the price and quantity effects:“border price effect” (area C), and the “import volume effect” (area E).Very useful in more complex diagrams.
16Trade volume effect & border price effect Can do same for Foreign gain rise, P’ to P”.Foreign gains from getting a higher price for the goods it sold before at P’ (border price effect), area D.And gains from selling more (trade volume effect), area F.
17The Workhorse: MD-MS Diagram Diagram very useful.easy identification of price and volume effects of a trade policy change.Welfare change likewise easy.eurosimportsMSMDImportsupply curvedemand curveImportsPFT
18MD-MS + open econ. supply & demand MD-MS diagram can be usefully teamed with open economy supply and demand diagram.Permits tracking domestic & international consequences of a trade policy change.eurosimportsquantityMSMDZCDomesticprice, eurosImportsupply curveDomestic demand curveImportsdemand curveSdomDdomPFT
19MFN Tariff Analysis1st step: determine how tariff changes prices and quantities.suppose tariff imposed equals T euros per unit.Small country ‘fiction’.Tariff shifts MS curve up by T.Exporters would need a domestic price that is T higher to offer the same exports.Because they earn the domestic price minus T.
20MFN Tariff AnalysisFor example, how high would domestic price have to be in Home for Foreigners to offer to export Ma to Home?Answer is Pa+T, so Foreigners would see a price of Pa.HomeimportsMDBorder priceForeignexportsXS=MSMS w/FTMS with TDomestic priceTPa2Pa+TMaXa=Ma1
21MFN Tariff AnalysisNew equilibrium in Home (MD=MS with T) is with P’ and M’.Domestic price now differs from border price (price exporters receive).P’ vs P’-T.Border priceDomestic priceMS with TMSXS=MSP’PFTPFTTP’-TMDForeignexportsHomeimportsM’MFTX’=M’XFT= MFT
22Positive effects Domestic price rises. Border price falls. Imports fall.Can’t see in diagram:Domestic consumption falls.domestic production rises.Foreign consumption rises.Foreign production falls.Could get this in diagram by adding open economy S & D diagram to right.
23Welfare effects: HomeDrop in imports creates loss equal area C. (Trade volume effect).Drop in border price creates gain equal to area B. (Border price effect, i.e. ToT effect).Net effect on Home = -C+B.ALTERNATIVELY:Private surplus change (sum of change in producer and consumer surplus) equal to minus A+C.Increase in tariff revenue equal to +A+B.Same net effect, B-C (but less intuition).
24Welfare effects: Foreign Drop in exports creates loss equal area D(Trade volume effect).Drop in border price creates loss equal to area B.(Border price effect, a.k.a., ToT effect).Net effect on Foreign = -D-B.ALTERNATIVELY:Private surplus change (sum of change in producer and consumer surplus) equal to minus -D-B.Same net effect, B-C (but less intuition).
25Welfare effects: useful compression In cases of more complex policy changes useful to do Home and Foreign welfare changes in one diagram.MS-MD diagram allows this:Home net welfare change is –C+B.Foreign net welfare change is –D-B.World welfare change is –D-C.NB: if Home gains (-C+B>0) it is because it exploits foreigners by ‘making’ them to pay part of the tariff (i.e. area B).Notice similarity with standard tax analysis.
26Distributional consequences: Home Trade protection imposed mainly due to politically considerations raised by distributional consequences.Thus important for some purposes to see domestic consequences of trade policy change.For this, add the open economy supply & demand diagram to the right of the MD-MS diagram.MD-MS diagram tells us the price and quantity effects of trade policy change.Open-economy S&D tells us the domestic distributional consequences.
27Distributional consequences: Home Home consumers lose, area E+C2+A+C1; Home producers gain E, Home tariff revenue rises by A+B.net change = B-C2+-C1 (this equals B-C in left panel).eurosimportsquantityMSMDCDomesticprice, eurosSdomDdomPFTZP’P’-TC’Z’ABDEC2C1
28A typology for trade barriers Many ways to categorise trade barriers.A useful 3-way categorisation.Focuses on ‘rents’ i.e. who earns the gap between domestic and border price?DCR (domestically captured rents) e.g. tariff, import licence.FCR (foreign captured rents), price undertakings, export taxes.Frictional (no rents since barriers involve real costs of importing/exporting), e.g.. Swedish wipers on headlights, paper recycling for carton boxes.
29A typology for trade barriers Net Home welfare changes for:DCR = B-CFCR = -A-CFrictional = -A-CNet Foreign welfare changes for:DCR = -B-DFCR = +A-DFrictional = -B-DNote: foreign may gain from FCR.eurosMSP’ACPFTDBP’-TMDM’MFTHomeimports